Piezoelectric actuator

ABSTRACT

A piezoelectric actuator includes a suspension plate, a piezoelectric ceramic plate, an outer frame and a bracket. The suspension plate is permitted to undergo a curvy vibration from a middle portion to a periphery portion. The piezoelectric ceramic plate is attached on the suspension plate. When a voltage is applied to the piezoelectric ceramic plate, the suspension plate is driven to undergo the curvy vibration. The outer frame is arranged around the suspension plate. The bracket is connected between the suspension plate and the outer frame for elastically supporting the suspension plate, and includes an intermediate part formed in a vacant space between the suspension plate and the outer frame and in parallel with the outer frame and the suspension plate, a first connecting part arranged between the intermediate part and the suspension plate, and a second connecting part arranged between the intermediate part and the outer frame.

FIELD OF THE INVENTION

The present invention relates to a piezoelectric actuator, and moreparticularly to a slim and silent piezoelectric actuator for a miniaturefluid control device.

BACKGROUND OF THE INVENTION

With the advancement of science and technology, fluid transportationdevices used in many sectors such as pharmaceutical industries, computertechniques, printing industries or energy industries are developedtoward elaboration and miniaturization. The fluid transportation devicesare important components that are used in for example micro pumps, microatomizers, printheads or industrial printers. Therefore, it is importantto provide an improved structure of the fluid transportation device.

For example, in the pharmaceutical industries, pneumatic devices orpneumatic machines use motors or pressure valves to transfer gases.However, due to the volume limitations of the motors and the pressurevalves, the pneumatic devices or the pneumatic machines are bulky involume. In other words, the conventional pneumatic device fails to meetthe miniaturization requirement, can't be installed in or cooperatedwith a portable equipment, and is not portable. Moreover, duringoperations of the motor or the pressure valve, annoying noise is readilygenerated. That is, the conventional pneumatic device is neitherfriendly nor comfortable to the user.

Therefore, there is a need of providing a piezoelectric actuator for aminiature fluid control device with small, miniature, silent, portableand comfortable benefits in order to eliminate the above drawbacks.

SUMMARY OF THE INVENTION

The present invention provides a piezoelectric actuator for a miniaturefluid control device, wherein the miniature fluid control device isemployed in a miniature pneumatic device for a portable or wearableequipment or machine. When a piezoelectric ceramic plate is operated ata high frequency, a pressure gradient is generated in the fluid channelsof a miniature fluid control device to facilitate the gas to flow at ahigh speed. Moreover, since there is an impedance difference between thefeeding direction and the exiting direction, the gas can be transmittedfrom the inlet side to the outlet side. Consequently, the miniaturepneumatic device is small, slim, portable and silent.

In accordance with an aspect of the present invention, a piezoelectricactuator is provided. The piezoelectric actuator includes a suspensionplate, a piezoelectric ceramic plate, an outer frame and at least onebracket. The suspension plate is a square structure. The suspensionplate is permitted to undergo a curvy vibration from a middle portion toa periphery portion. A length of the suspension plate is in a rangebetween 4 mm and 8 mm. The piezoelectric ceramic plate is a squarestructure and has a length not larger than a length of the suspensionplate. The piezoelectric ceramic plate is attached on a first surface ofthe suspension plate. When a voltage is applied to the piezoelectricceramic plate, the suspension plate is driven to undergo the curvyvibration. The outer frame is arranged around the suspension plate. Theat least one bracket is connected between the suspension plate and theouter frame for elastically supporting the suspension plate. The bracketincludes an intermediate part, a first connecting part and a secondconnecting part. The intermediate part is formed in a vacant spacebetween the suspension plate and the outer frame and in parallel withthe outer frame and the suspension plate. The first connecting part isarranged between the intermediate part and the suspension plate. Thesecond connecting part is arranged between the intermediate part and theouter frame. The first connecting part and the second connecting partare opposed to each other and arranged along the same horizontal line.

The above contents of the present invention will become more readilyapparent to those ordinarily skilled in the art after reviewing thefollowing detailed description and accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic exploded view illustrating a miniature pneumaticdevice according to an embodiment of the present invention and takenalong a first viewpoint;

FIG. 1B is a schematic assembled view illustrating the miniaturepneumatic device of FIG. 1A;

FIG. 2A is a schematic exploded view illustrating the miniaturepneumatic device according to the embodiment of the present inventionand taken along a second viewpoint;

FIG. 2B is a schematic assembled view illustrating the miniaturepneumatic device of FIG. 2A;

FIG. 3A is a schematic perspective view illustrating the piezoelectricactuator of the miniature pneumatic device of FIG. 1A and taken alongthe front side;

FIG. 3B is a schematic perspective view illustrating the piezoelectricactuator of the miniature pneumatic device of FIG. 1A and taken alongthe rear side;

FIG. 3C is a schematic cross-sectional view illustrating thepiezoelectric actuator of the miniature pneumatic device of FIG. 1A;

FIGS. 4A to 4C schematically illustrate various exemplary piezoelectricactuator used in the miniature pneumatic device of the presentinvention;

FIGS. 5A to 5E schematically illustrate the actions of the miniaturefluid control device of the miniature pneumatic device of FIG. 1A;

FIG. 6A schematically illustrate a gas-collecting operation of the gascollecting plate and miniature valve device of the miniature pneumaticdevice of FIG. 1A;

FIG. 6B schematically illustrate a gas-releasing operation of the gascollecting plate and miniature valve device of the miniature pneumaticdevice of FIG. 1A;

FIGS. 7A to 7E schematically illustrate a gas-collecting operation ofthe miniature pneumatic device of FIG. 1A; and

FIG. 8 schematically illustrate the gas-releasing actions or thepressure-reducing actions of the miniature pneumatic device of FIG. 1A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will now be described more specifically withreference to the following embodiments. It is to be noted that thefollowing descriptions of preferred embodiments of this invention arepresented herein for purpose of illustration and description only. It isnot intended to be exhaustive or to be limited to the precise formdisclosed.

The present invention provides a miniature pneumatic device. Theminiature pneumatic device may be used in many sectors such aspharmaceutical industries, energy industries, computer techniques orprinting industries for transporting gases.

Please refer to FIGS. 1A, 1B, 2A, 2B and 7A to 7E. FIG. 1A is aschematic exploded view illustrating a miniature pneumatic deviceaccording to an embodiment of the present invention and taken along afirst viewpoint. FIG. 1B is a schematic assembled view illustrating theminiature pneumatic device of FIG. 1A. FIG. 2A is a schematic explodedview illustrating the miniature pneumatic device according to theembodiment of the present invention and taken along a second viewpoint.FIG. 2B is a schematic assembled view illustrating the miniaturepneumatic device of FIG. 2A. FIGS. 7A to 7E schematically illustrate agas-collecting operation of the miniature pneumatic device of FIG. 1A.

As shown in FIGS. 1A and 2A, the miniature pneumatic device 1 comprisesa miniature fluid control device 1A and a miniature valve device 1B. Inthis embodiment, the miniature fluid control device 1A comprises ahousing 1 a, a piezoelectric actuator 13, a first insulation plate 141,a conducting plate 15 and a second insulation plate 142. The housing 1 acomprises a gas collecting plate 16 and a base 10. The base 10 comprisesa gas inlet plate 11 and a resonance plate 12. The piezoelectricactuator 13 is aligned with the resonance plate 12. The gas inlet plate11, the resonance plate 12, the piezoelectric actuator 13, the firstinsulation plate 141, the conducting plate 15, the second insulationplate 142 and the gas collecting plate 16 are stacked on each othersequentially. Moreover, the piezoelectric actuator 13 comprises asuspension plate 130, an outer frame 131, at least one bracket 132 and apiezoelectric ceramic plate 133. In this embodiment, the miniature valvedevice 1B comprises a valve plate 17 and a gas outlet plate 18.

As shown in FIG. 1A, the gas collecting plate 16 comprises a bottomplate and a sidewall 168. The sidewall 168 is protruded from the edgesof the bottom plate. The length of the gas collecting plate 16 is in therange between 9 mm and 17 mm. The width of the gas collecting plate 16is in the range between 9 mm and 17 mm. Preferably, the length/widthratio of the gas collecting plate 16 is in the range between 0.53 and1.88. Moreover, an accommodation space 16 a is defined by the bottomplate and the sidewall 168 collaboratively. The piezoelectric actuator13 is disposed within the accommodation space 16 a. After the miniaturepneumatic device 1 is assembled, the resulting structure of theminiature pneumatic device taken from the front side is shown in FIG. 1Band FIGS. 7A to 7E. The miniature fluid control device 1A and theminiature valve device 1B are combined together. That is, the valveplate 17 and the gas outlet plate 18 of the miniature valve device 1Bare stacked on each other and positioned on the gas collecting plate 16of the miniature fluid control device 1A. The gas outlet plate 18comprises a pressure-releasing perforation 181 and an outlet structure19. The outlet structure 19 is in communication with an equipment (notshown). When the gas in the miniature valve device 1B releases from thepressure-releasing perforation 181, the pressure-releasing purpose isachieved.

After the miniature fluid control device 1A and the miniature valvedevice 1B are combined together, the miniature pneumatic device 1 isassembled. Consequently, a gas is fed into the miniature fluid controldevice 1A through at least one inlet 110 of the gas inlet plate 11. Inresponse to the actions of the piezoelectric actuator 13, the gas istransferred downwardly through plural pressure chambers (not shown).Then, the gas is transferred through the miniature valve device 1B inone direction. The pressure of the gas is accumulated in an equipment(not shown) that is in communication with the outlet structure 19 of theminiature valve device 1B. For releasing the pressure, the output gasamount of the miniature fluid control device 1A is exited from thepressure-releasing perforation 181 of the gas outlet plate 18 of theminiature valve device 1B.

Please refer to FIGS. 1A and 2A again. The gas inlet plate 11 of theminiature fluid control device 1A comprises a first surface 11 b, asecond surface 11 a and the at least one inlet 110. In this embodiment,the gas inlet plate 11 comprises four inlets 110. The inlets 110 runthrough the first surface 11 b and the second surface 11 a of the gasinlet plate 11. In response to the action of the atmospheric pressure,the gas can be introduced into the miniature fluid control device 1Athrough the at least one inlet 110. As shown in FIG. 2A, at least oneconvergence channel 112 is formed in the first surface 11 b of the gasinlet plate 11. The at least one convergence channel 112 is incommunication with the at least one inlet 110 in the second surface 11 aof the gas inlet plate 11. The number of the at least one convergencechannel 112 is identical to the number of the at least one inlet 110. Inthis embodiment, the gas inlet plate 11 comprises four convergencechannels 112. It is noted that the number of the at least oneconvergence channel 112 and the number of the at least one inlet 110 maybe varied according to the practical requirements. Moreover, a centralcavity 111 is formed in the first surface 11 b of the gas inlet plate 11and located at a central convergence area of the four convergencechannels 112. The central cavity 111 is in communication with the atleast one convergence channel 112. After the gas is introduced into theat least one convergence channel 112 through the at least one inlet 110,the gas is guided to the central cavity 111. In this embodiment, the atleast one inlet 110, the at least one convergence channel 112 and thecentral cavity 111 of the gas inlet plate 11 are integrally formed. Thecentral cavity 111 is a convergence chamber for temporarily storing thegas.

Preferably but not exclusively, the gas inlet plate 11 is made ofstainless steel. The thickness of the gas inlet plate 11 is in the rangebetween 0.4 mm and 0.6 mm, and preferably 0.5 mm. Moreover, the depth ofthe convergence chamber defined by the central cavity 111 and the depthof the at least one convergence channel 112 are equal. For example, thedepth of the convergence chamber and the depth of the at least oneconvergence channel 112 are in the range between 0.2 mm and 0.3 mm.Preferably but not exclusively, the resonance plate 12 is made offlexible material. The resonance plate 12 comprises a central aperture120 corresponding to the central cavity 111 of the gas inlet plate 11.Consequently, the gas can be transferred downwardly through the centralaperture 120. Preferably but not exclusively, the resonance plate 12 ismade of copper. The thickness of the resonance plate 12 is in the rangebetween 0.03 mm and 0.08 mm, and preferably 0.05 mm.

FIG. 3A is a schematic perspective view illustrating the piezoelectricactuator of the miniature pneumatic device of FIG. 1A and taken alongthe front side. FIG. 3B is a schematic perspective view illustrating thepiezoelectric actuator of the miniature pneumatic device of FIG. 1A andtaken along the rear side. FIG. 3C is a schematic cross-sectional viewillustrating the piezoelectric actuator of the miniature pneumaticdevice of FIG. 1A. As shown in FIGS. 3A, 3B and 3C, the piezoelectricactuator 13 comprises the suspension plate 130, the outer frame 131, theat least one bracket 132, and the piezoelectric ceramic plate 133. Thepiezoelectric ceramic plate 133 is attached on a first surface 130 b ofthe suspension plate 130. The piezoelectric ceramic plate 133 issubjected to a curvy vibration in response to an applied voltage. Thesuspension plate 130 comprises a middle portion 130 d and a peripheryportion 130 e. When the piezoelectric ceramic plate 133 is subjected tothe curvy vibration, the suspension plate 130 is subjected to the curvyvibration from the middle portion 130 d to the periphery portion 130 e.The at least one bracket 132 is arranged between the suspension plate130 and the outer frame 131. That is, the at least one bracket 132 isconnected between the suspension plate 130 and the outer frame 131. Thetwo ends of the bracket 132 are connected with the outer frame 131 andthe suspension plate 130, respectively. Consequently, the bracket 131can elastically support the suspension plate 130. Moreover, at least onevacant space 135 is formed between the bracket 132, the suspension plate130 and the outer frame 131 for allowing the gas to go through. The typeof the suspension plate 130 and the outer frame 131 and the type and thenumber of the at least one bracket 132 may be varied according to thepractical requirements. Moreover, a conducting pin 134 is protrudedoutwardly from the outer frame 131 so as to be electrically connectedwith an external circuit (not shown).

In this embodiment, the suspension plate 130 is a stepped structure.That is, the suspension plate 130 comprises a bulge 130 c. The bulge 130c is formed on a second surface 130 a of the suspension plate 130. Forexample, the bulge 130 c is a circular convex structure. The thicknessof the bulge 130 c is in the range between 0.02 mm and 0.08 mm, andpreferably 0.03 mm. Preferably but not exclusively, the diameter of thebulge 130 c is 0.55 times the short side length of the suspension plate130. As shown in FIGS. 3A and 3C, a top surface of the bulge 130 c ofthe suspension plate 130 is coplanar with a second surface 131 a of theouter frame 131, and the second surface 130 a of the suspension plate130 is coplanar with a second surface 132 a of the bracket 132.Moreover, the bulge 130 c of the suspension plate 130 (or the secondsurface 131 a of the outer frame 131) has a specified thickness withrespect to the second surface 130 a of the suspension plate 130 (or thesecond surface 132 a of the bracket 132). As shown in FIGS. 3B and 3C, afirst surface 130 b of the suspension plate 130, a first surface 131 bof the outer frame 131 and a first surface 132 b of the bracket 132 arecoplanar with each other. The piezoelectric ceramic plate 133 isattached on the first surface 130 b of the suspension plate 130. In someother embodiments, the suspension plate 130 is a square plate structurewith two flat surfaces. That is, the structure of the suspension plate130 may be varied according to the practical requirements. In thisembodiment, the suspension plate 130, the at least bracket 132 and theouter frame 131 are integrally formed and produced by using a metalplate (e.g., a stainless steel plate). The thickness of the suspensionplate 130 is in the range between 0.1 mm and 0.4 mm, and preferably 0.27mm. The length of the suspension plate 130 is in the range between 4 mmand 8 mm, and preferably in the range between 6 mm and 8 mm. The widthof the suspension plate 130 is in the range between 4 mm and 8 mm, andpreferably in the range between 6 mm and 8 mm. The thickness of theouter frame 131 is in the range between 0.2 mm and 0.4 mm, andpreferably 0.3 mm.

The thickness of the piezoelectric ceramic plate 133 is in the rangebetween 0.05 mm and 0.3 mm, and preferably 0.10 mm. The length of thepiezoelectric ceramic plate 133 is not larger than the length of thesuspension plate 130. The length of the piezoelectric ceramic plate 133is in the range between 4 mm and 8 mm, and preferably in the rangebetween 6 mm and 8 mm. The width of the piezoelectric ceramic plate 133is in the range between 4 mm and 8 mm, and preferably in the rangebetween 6 mm and 8 mm. Moreover, the length/width ratio of thepiezoelectric ceramic plate 133 is in the range between 0.5 and 2. Insome embodiments, the length of the piezoelectric ceramic plate 133 issmaller than the length of the suspension plate 130. Similarly, thepiezoelectric ceramic plate 133 is a square plate structurecorresponding to the suspension plate 130.

Preferably, the suspension plate 130 of the piezoelectric actuator 13used in the miniature pneumatic device 1 of the present invention is asquare suspension plate. In comparison with the circular suspensionplate (e.g., the circular suspension plate j0 as shown in FIG. 4A), thesquare suspension plate is more power-saving.

Generally, the consumed power of the capacitive load at the resonancefrequency is positively related to the resonance frequency. Since theresonance frequency of the square suspension plate is obviously lowerthan that of the circular square suspension plate, the consumed power ofthe square suspension plate is lower. Since the square suspension plateis more power-saving than the circular suspension plate, the squaresuspension plate is suitably used in the wearable device.

FIGS. 4A, 4B and 4C schematically illustrate various exemplarypiezoelectric actuator used in the miniature pneumatic device of thepresent invention. As shown in the drawings, the suspension plate 130,the outer frame 131 and the at least one bracket 132 of thepiezoelectric actuator 13 have various types.

FIG. 4A schematically illustrates the types (a)˜(l) of the piezoelectricactuator. In the type (a), the outer frame a1 and the suspension platea0 are square, the outer frame a1 and the suspension plate a0 areconnected with each other through eight brackets a2, and a vacant spacea3 is formed between the brackets a2, the suspension plate a0 and theouter frame a1 for allowing the gas to go through. In the type (i), theouter frame i1 and the suspension plate i0 are also square, but theouter frame i1 and the suspension plate i0 are connected with each otherthrough two brackets i2. In addition, the outer frame and the suspensionplate in each of the types (b)˜(h) are also square. In each of the types(j)˜(l), the suspension plate is circular, and the outer frame has asquare with arc-shaped corners. For example, in the type (j), thesuspension plate j0 is circular, and the outer frame has a square witharc-shaped corners.

FIG. 4B schematically illustrates the types (m)˜(r) of the piezoelectricactuator. In these types (m)˜(r), the suspension plate 130 and the outerframe 131 are square. In the type (m), the outer frame m1 and thesuspension plate m0 are square, the outer frame m1 and the suspensionplate m0 are connected with each other through four brackets m2, and avacant space m3 is formed between the brackets m2, the suspension platem0 and the outer frame m1 for allowing the gas to go through. Thebracket m2 between the outer frame m1 and the suspension plate m0 is aconnecting part. The bracket m2 has two ends m2′ and m2″. The end m2′ ofthe bracket m2 is connected with the outer frame m1. The end m2″ of thebracket m2 is connected with the suspension plate m0. The two ends m2′and m2″ are opposed to each other and arranged along the same horizontalline. In the type (n), the outer frame n1 and the suspension plate m0are square, the outer frame n1 and the suspension plate n0 are connectedwith each other through four brackets n2, and a vacant space n3 isformed between the brackets n2, the suspension plate n0 and the outerframe n1 for allowing the gas to go through. The bracket n2 between theouter frame n1 and the suspension plate n0 is a connecting part. Thebracket n2 has two ends n2′ and n2″. The end n2′ of the bracket n2 isconnected with the outer frame n1. The end n2″ of the bracket n2 isconnected with the suspension plate n0. The two ends n2′ and n2″ are notarranged along the same horizontal line. For example, the two ends n2′and n2″ are inclined at 0˜45 degrees with respect to the horizontalline, and the two ends n2′ and n2″ are interlaced. In the type (o), theouter frame of and the suspension plate o0 are square, the outer frameof and the suspension plate o0 are connected with each other throughfour brackets o2, and a vacant space o3 is formed between the bracketso2, the suspension plate o0 and the outer frame of for allowing the gasto go through. The bracket o2 between the outer frame o1 and thesuspension plate o0 is a connecting part. The bracket o2 has two endso2′ and o2″. The end o2′ of the bracket o2 is connected with the outerframe o1. The end o2″ of the bracket o2 is connected with the suspensionplate o0. The two ends o2′ and o2″ are opposed to each other andarranged along the same horizontal line. In comparison with the abovetypes, the profile of the bracket o2 is distinguished.

In the type (p), the outer frame p1 and the suspension plate p0 aresquare, the outer frame p1 and the suspension plate p0 are connectedwith each other through four brackets p2, and a vacant space p3 isformed between the brackets p2, the suspension plate p0 and the outerframe p1 for allowing the gas to go through. The bracket p2 between theouter frame p1 and the suspension plate p0 comprises a first connectingpart p20, an intermediate part p21 and a second connecting part p22. Theintermediate part p21 is formed in the vacant space p3 and in parallelwith the outer frame p1 and the suspension plate p0. The firstconnecting part p20 is arranged between the intermediate part p21 andthe suspension plate p0. The second connecting part p22 is arrangedbetween the intermediate part p21 and the outer frame p1. The firstconnecting part p20 and the second connecting part p22 are opposed toeach other and arranged along the same horizontal line.

In the type (q), the outer frame q1, the suspension plate q0, thebracket q2 and the vacant space q3 are similar to those of the type (m)and the type (o). However, the structure of the bracket q2 isdistinguished. The suspension plate q0 is square. Each side of thesuspension plate q0 is connected with the corresponding side of theouter frame q1 through two connecting parts q2. The two ends q2′ and q2″of each connecting part q2 are opposed to each other and arranged alongthe same horizontal line. In the type (r), the outer frame r1, thesuspension plate r0, the bracket r2 and the vacant space r3 are similarto those of the above embodiments. However, the bracket r2 is a V-shapedconnecting part. That is, the bracket r2 is connected with the outerframe r1 and the suspension plate r0 at an inclined angle 0˜45 degrees.An end r2″ of the bracket r2 is connected with the suspension plate r0,and two ends r2′ of the bracket r2 is connected with the outer frame r1.That is, the ends b2′ and b″ are not arranged along the same horizontalline.

FIG. 4C schematically illustrates the types (s)˜(x) of the piezoelectricactuator. The structures of the types (s)˜(x) are similar to those ofthe types (m)˜(r), respectively. However, in the types (s)˜(x), thesuspension plate 130 of the piezoelectric actuator 13 has a bulge 130 c.The bulges 130 c in the types (s)˜(x) are indicated as s4, t4, u4, v4,w4 and x4, respectively. The suspension plate 130 is square, and thusthe power-saving efficacy is achieved. As mentioned above, the steppedstructure comprising the bulge and the square plate structure with twoflat surfaces are suitably used as the suspension plates of the presentinvention. Moreover, the number of the brackets 132 between the outerframe 131 and the suspension plate 130 may be varied according to thepractical requirements. Moreover, the suspension plate 130, the outerframe 131 and the at least one bracket 132 are integrally formed witheach other and produced by a conventional machining process, aphotolithography and etching process, a laser machining process, anelectroforming process, an electric discharge machining process and soon.

Please refer to FIGS. 1A and 2A again. The miniature fluid controldevice 1A further comprises the first insulation plate 141, theconducting plate 15 and the second insulation plate 142. The firstinsulation plate 141, the conducting plate 15 and the second insulationplate 142 are stacked on each other sequentially and located under thepiezoelectric actuator 13. The profiles of the first insulation plate141, the conducting plate 15 and the second insulation plate 142substantially match the profile of the outer frame 131 of thepiezoelectric actuator 13. The first insulation plate 141 and the secondinsulation plate 142 are made of an insulating material (e.g. a plasticmaterial) for providing insulating efficacy. The conducting plate 15 ismade of an electrically conductive material (e.g. a metallic material)for providing electrically conducting efficacy. Moreover, the conductingplate 15 has a conducting pin 151 so as to be electrically connectedwith an external circuit (not shown).

FIGS. 5A to 5E schematically illustrate the actions of the miniaturefluid control device of the miniature pneumatic device of FIG. 1A. Asshown in FIG. 5A, the gas inlet plate 11, the resonance plate 12, thepiezoelectric actuator 13, the first insulation plate 141, theconducting plate 15 and the second insulation plate 142 of the miniaturefluid control device 1A are stacked on each other sequentially.Moreover, there is a gap g0 between the resonance plate 12 and the outerframe 131 of the piezoelectric actuator 13. In this embodiment, a filler(e.g. a conductive adhesive) is inserted into the gap g0. Consequently,the depth of the gap g0 between the resonance plate 12 and the bulge 130c of the suspension plate 130 can be maintained to guide the gas to flowmore quickly. Moreover, due to the proper distance between the resonanceplate 12 and the bulge 130 c of the suspension plate 130, the contactinterference is reduced and the generated noise is largely reduced.

Please refer to FIGS. 5A to 5E again. After the gas inlet plate 11, theresonance plate 12 and the piezoelectric actuator 13 are combinedtogether, a convergence chamber for converging the gas is defined by thecentral aperture 120 of the resonance plate 12 and the gas inlet plate11 collaboratively, and a first chamber 121 is formed between theresonance plate 12 and the piezoelectric actuator 13 for temporarilystoring the gas. Through the central aperture 120 of the resonance plate12, the first chamber 121 is in communication with the central cavity111 that is formed in the first surface 11 b of the gas inlet plate 11.The peripheral regions of the first chamber 121 are in communicationwith the underlying miniature valve device 1B through the vacant space135 of the piezoelectric actuator 13.

When the miniature fluid control device 1A of the miniature pneumaticdevice 1 is enabled, the piezoelectric actuator 13 is actuated by anapplied voltage. Consequently, the piezoelectric actuator 13 is vibratedalong a vertical direction in a reciprocating manner by using thebracket 132 as a fulcrum. The resonance plate 12 is light and thin.Please refer to FIG. 5B. When the piezoelectric actuator 13 is vibrateddownwardly in response to the applied voltage, the resonance plate 12 isvibrated along the vertical direction in the reciprocating mannerbecause of the resonance of the piezoelectric actuator 13. Moreespecially, the portion of the resonance plate 12 corresponding to thecentral cavity 111 of the gas inlet plate 11 is also subjected to acurvy deformation. Hereinafter, the region of the resonance plate 12corresponding to the central cavity 111 of the gas inlet plate 11 isalso referred as a movable part 12 a of the resonance plate 12. When thepiezoelectric actuator 13 is vibrated downwardly, the movable part 12 aof the resonance plate 12 is subjected to the curvy deformation becausethe movable part 12 a of the resonance plate 12 is pushed by the gas andvibrated in response to the piezoelectric actuator 13. After the gas isfed into the at least one inlet 110 of the gas inlet plate 11, the gasis transferred to the central cavity 111 of the gas inlet plate 11through the at least one convergence channel 112. Then, the gas istransferred through the central aperture 120 of the resonance plate 12,and introduced downwardly into the first chamber 121. As thepiezoelectric actuator 13 is actuated, the resonance of the resonanceplate 12 occurs. Consequently, the movable part 12 of the resonanceplate 12 is also vibrated along the vertical direction in thereciprocating manner.

As shown in FIG. 5C, the resonance plate 12 is vibrated downwardly andcontacted with the bulge 130 c of the suspension plate 130 of thepiezoelectric actuator 13. The region of the resonance plate 12excluding the movable part 12 a is also referred as a fixed part 12 b.Meanwhile, the gap between the suspension plate 130 and the fixed part12 b of the resonance plate 12 is not reduced. Due to the deformation ofthe resonance plate 12, the volume of the first chamber 121 is shrunkenand a middle communication space of the first chamber 121 is closed.Under this circumstance, the gas is pushed toward peripheral regions ofthe first chamber 121. Consequently, the gas is transferred downwardlythrough the vacant space 135 of the piezoelectric actuator 13.

As shown in FIG. 5D, the resonance plate 12 is returned to its originalposition after the movable part 12 a of the resonance plate 12 issubjected to the curvy deformation. Then, the piezoelectric actuator 13is vibrated upwardly in response to the applied voltage. Consequently,the volume of the first chamber 121 is also shrunken. Since thepiezoelectric actuator 13 is ascended at a vibration displacement d, thegas is continuously pushed toward peripheral regions of the firstchamber 121. Meanwhile, the gas is continuously fed into the at leastone inlet 110 of the gas inlet plate 11, and transferred to the centralcavity 111.

Then, as shown in FIG. 5E, the resonance plate 12 is moved upwardlybecause the piezoelectric actuator 13 is vibrated upwardly. That is, themovable part 12 a of the resonance plate 12 is moved upwardly. Underthis circumstance, the gas in the central cavity 111 is transferred tothe first chamber 121 through the central aperture 120 of the resonanceplate 12, then the gas is transferred downwardly through the vacantspace 135 of the piezoelectric actuator 13, and finally the gas isexited from the miniature fluid control device 1A.

From the above discussions, when the resonance plate 12 is vibratedalong the vertical direction in the reciprocating manner, the gap g0between the resonance plate 12 and the piezoelectric actuator 13 ishelpful to increase the amplitude of the resonance plate 12. That is,due to the gap g0 between the resonance plate 12 and the piezoelectricactuator 13, the amplitude of the resonance plate 12 is increased whenthe resonance occurs. The difference x between the gap g0 and thevibration displacement d of the piezoelectric actuator 13 is given by aformula: x=g0−d. A series of tests about the maximum output pressure ofthe miniature pneumatic device 1 corresponding to different values of xare performed. In case that x≦0 μm, the miniature pneumatic device 1generates noise. In case that x=1˜5 μm, the maximum output pressure ofthe miniature pneumatic device 1 is 350 mmHg. In case that x=5˜10 μm,the maximum output pressure of the miniature pneumatic device 1 is 250mmHg. In case that x=10˜15 μm, the maximum output pressure of theminiature pneumatic device 1 is 150 mmHg. The relationships between thedifference x and the maximum output pressure are listed in Table 1. Thevalues of Table 1 are obtained when the operating frequency is in therange between 17 kHz and 20 kHz and the operating voltage is in therange between ±10V and ±20V. Consequently, a pressure gradient isgenerated in the fluid channels of the miniature fluid control device 1Ato facilitate the gas to flow at a high speed. Moreover, since there isan impedance difference between the feeding direction and the exitingdirection, the gas can be transmitted from the inlet side to the outletside. Moreover, even if the outlet side has a gas pressure, theminiature fluid control device 1A still has the capability of pushingout the gas while achieving the silent efficacy.

TABLE 1 Test x Maximum output pressure 1 x = 1~5 μm 350 mmHg 2 x = 5~10μm 250 mmHg 3 x = 10~15 μm 150 mmHg

In some embodiments, the vibration frequency of the resonance plate 12along the vertical direction in the reciprocating manner is identical tothe vibration frequency of the piezoelectric actuator 13. That is, theresonance plate 12 and the piezoelectric actuator 13 are synchronouslyvibrated along the upward direction or the downward direction. It isnoted that numerous modifications and alterations of the actions of theminiature fluid control device 1A may be made while retaining theteachings of the invention.

Please refer to FIGS. 1A, 2A, 6A and 6B. FIG. 6A schematicallyillustrate a gas-collecting operation of the gas collecting plate andminiature valve device of the miniature pneumatic device of FIG. 1A.FIG. 6B schematically illustrate a gas-releasing operation of the gascollecting plate and miniature valve device of the miniature pneumaticdevice of FIG. 1A. As shown in FIGS. 1A and 6A, the valve plate 17 andthe gas outlet plate 18 of the miniature valve device 1B are stacked oneach other sequentially. Moreover, the miniature valve device 1B and thegas collecting plate 16 of the miniature fluid control device 1Acooperate with each other.

The gas collecting plate 16 comprises a first surface 160 and a secondsurface 161 (also referred as a fiducial surface). The first surface 160of the gas collecting plate 16 is concaved to define a gas-collectingchamber 162. The piezoelectric actuator 13 is accommodated within thegas-collecting chamber 162. The gas that is transferred downwardly bythe miniature fluid control device 1A is temporarily accumulated in thegas-collecting chamber 162. The gas collecting plate 16 comprises afirst perforation 163 and a second perforation 164. A first end of thefirst perforation 163 and a first end of the second perforation 164 arein communication with the gas-collecting chamber 162. A second end ofthe first perforation 163 and a second end of the second perforation 164are in communication with a first pressure-releasing chamber 165 and afirst outlet chamber 166, which are formed in the second surface 161 ofthe gas collecting plate 16. Moreover, the gas collecting plate 16 has araised structure 167 corresponding to the first outlet chamber 166. Forexample, the raised structure 167 includes but is not limited to acylindrical post. The raised structure 167 is located at a level higherthan the second surface 161 of the gas collecting plate 16. Moreover, athickness of the raised structure 167 is in a range between 0.3 mm and0.55 mm, and preferably 0.4 mm.

The gas outlet plate 18 comprises a pressure-releasing perforation 181,an outlet perforation 182, a first surface 180 (also referred as afiducial surface) and a second surface 187. The pressure-releasingperforation 181 and the outlet perforation 182 run through the firstsurface 180 and the second surface 187. The first surface 180 of the gasoutlet plate 18 is concaved to define a second pressure-releasingchamber 183 and a second outlet chamber 184. The pressure-releasingperforation 181 is located at a center of the second pressure-releasingchamber 183. Moreover, the gas outlet plate 18 further comprises acommunication channel 185 between the second pressure-releasing chamber183 and the second outlet chamber 184 for allowing the gas to gothrough. A first end of the outlet perforation 182 is in communicationwith the second outlet chamber 184. A second end of the outletperforation 182 is in communication with an outlet structure 19. Theoutlet structure 19 is in connected with an equipment (not shown). Theequipment is for example but not limited to a gas-pressure drivingequipment.

The valve plate 17 comprises a valve opening 170 and plural positioningopenings 171 (see FIG. 1A). The thickness of the valve plate 17 is inthe range between 0.1 mm and 0.3 mm, and preferably 0.2 mm.

After the gas collecting plate 16, the valve plate 17 and the gas outletplate 18 are combined together, the pressure-releasing perforation 181of the gas outlet plate 18 is aligned with the first perforation 163 ofthe gas collecting plate 16, the second pressure-releasing chamber 183of the gas outlet plate 18 is aligned with the first pressure-releasingchamber 165 of the gas collecting plate 16, and the second outletchamber 184 of the gas outlet plate 18 is aligned with the first outletchamber 166 of the gas collecting plate 16. The valve plate 17 isarranged between the gas collecting plate 16 and the gas outlet plate 18for blocking the communication between the first pressure-releasingchamber 165 and the second pressure-releasing chamber 183. The valveopening 170 of the valve plate 17 is arranged between the secondperforation 164 and the outlet perforation 182. Moreover, the valveopening 170 of the valve plate 17 is aligned with the raised structure167 corresponding to the first outlet chamber 166 of the gas collectingplate 16. Due to the arrangement of the single valve opening 170, thegas is transferred through the miniature valve device 1B in onedirection in response to the pressure difference.

In this embodiment, the gas outlet plate 18 has the convex structure 181a beside a first end of the pressure-releasing perforation 181.Preferably but not exclusively, the convex structure 181 a is acylindrical post. The thickness of the convex structure 181 a is in therange between 0.3 mm and 0.55 mm, and preferably 0.4 mm. The top surfaceof the convex structure 181 a is located at a level higher than thefirst surface 180 of the gas outlet plate 18. Consequently, thepressure-releasing perforation 181 can be quickly contacted with andclosed by the valve plate 17. Moreover, the convex structure 181 a canprovide a pre-force to achieve a good sealing effect. In thisembodiment, the gas outlet plate 18 further comprises aposition-limiting structure 188. The thickness of the position-limitingstructure 188 is 0.32 mm. The position-limiting structure 188 isdisposed within the second pressure-releasing chamber 183. Preferablybut not exclusively, the position-limiting structure 188 is aring-shaped structure. While the gas-collecting operation of theminiature valve device 1B is performed, the position-limiting structure188 can assist in supporting the valve plate 17 and avoid collapse ofthe valve plate 17. Consequently, the valve plate 17 can be opened orclosed more quickly.

Hereinafter, the gas-collecting operation of the miniature valve device1B will be illustrated with reference to FIG. 6A. In case that the gasfrom the miniature fluid control device 1A is transferred downwardly tothe miniature valve device 1B or the ambient air pressure is higher thanthe inner pressure of the equipment which is in communication with theoutlet structure 19, the gas will be transferred from the miniaturefluid control device 1A to the gas-collecting chamber 162 of the gascollecting plate 16. Then, the gas is transferred downwardly to thefirst pressure-releasing chamber 165 and the first outlet chamber 166through the first perforation 163 and the second perforation 164. Inresponse to the downward gas, the flexible valve plate 17 is subjectedto a downward curvy deformation. Consequently, the volume of the firstpressure-releasing chamber 165 is expanded, and the valve plate 17 is inclose contact with the first end of the pressure-releasing perforation181 corresponding to the first perforation 163. Under this circumstance,the pressure-releasing perforation 181 of the gas outlet plate 18 isclosed, and thus the gas within the second pressure-releasing chamber183 is not leaked out from the pressure-releasing perforation 181. Inthis embodiment, the gas outlet plate 18 has the convex structure 181 abeside of the first end of the pressure-releasing perforation 181. Dueto the arrangement of the convex structure 181 a, the pressure-releasingperforation 181 can be quickly closed by the valve plate 17. Moreover,the convex structure 181 a can provide a pre-force to achieve a goodsealing effect. The position-limiting structure 188 is arranged aroundthe pressure-releasing perforation 181 to assist in supporting the valveplate 17 and avoid collapse of the valve plate 17. On the other hand,the gas is transferred downwardly to the first outlet chamber 166through the second perforation 164. In response to the downward gas, thevalve plate 17 corresponding to the first outlet chamber 166 is alsosubjected to the downward curvy deformation. Consequently, the valveopening 170 of the valve membrane 17 is correspondingly opened to thedownward side. Under this circumstance, the gas is transferred from thefirst outlet chamber 166 to the second outlet chamber 184 through thevalve opening 170. Then, the gas is transferred to the outlet structure19 through the outlet perforation 182 and then transferred to theequipment which is in communication with the outlet structure 19.Consequently, the purpose of collecting the gas pressure is achieved.

Hereinafter, the gas-releasing operation of the miniature valve device1B will be illustrated with reference to FIG. 6B. For performing thegas-releasing operation, the user may adjust the amount of the gas to befed into the miniature fluid control device 1A, so that the gas is nolonger transferred to the gas-collecting chamber 162. Alternatively, incase that the inner pressure of the equipment which is in communicationwith the outlet structure 19 is higher than the ambient air pressure,the gas-releasing operation may be performed. Under this circumstance,the gas is transferred from the outlet structure 19 to the second outletchamber 184 through the outlet perforation 182. Consequently, the volumeof the second outlet chamber 184 is expanded, and the flexible valveplate 17 corresponding to the second outlet chamber 184 is subjected tothe upward curvy deformation. In addition, the valve plate 17 is inclose contact with the gas collecting plate 16. Consequently, the valveopening 170 of the valve plate 17 is closed by the gas collecting plate16. Moreover, the gas collecting plate 16 has the raised structure 167corresponding to the first outlet chamber 166. Due to the arrangement ofthe raised structure 167, the flexible valve plate 17 can be bentupwardly more quickly. Moreover, the raised structure 167 can provide apre-force to achieve a good sealing effect of the valve opening 170.Since the valve opening 170 of the valve plate 17 is contacted with andclosed by the raised structure 167, the gas in the second outlet chamber184 will not be reversely returned to the first outlet chamber 166.Consequently, the efficacy of avoiding gas leakage is enhanced.Moreover, since the gas in the second outlet chamber 184 is transferredto the second pressure-releasing chamber 183 through the communicationchannel 185, the volume of the second pressure-releasing chamber 183 isexpanded. Consequently, the valve plate 17 corresponding to the secondpressure-releasing chamber 183 is also subjected to the upward curvydeformation. Since the valve plate 17 is no longer in contact with thefirst end of the pressure-releasing perforation 181, thepressure-releasing perforation 181 is opened. Under this circumstance,the gas in the second pressure-releasing chamber 183 is outputtedthrough the pressure-releasing perforation 181. Consequently, thepressure of the gas is released. Similarly, due to the convex structure181 a beside the pressure-releasing perforation 181 or theposition-limiting structure 188 within the second pressure-releasingchamber 183, the flexible valve plate 17 can be subjected to the upwardcurvy deformation more quickly. Consequently, the pressure-releasingperforation 181 can be quickly opened. After the gas-releasing operationin one direction is performed, the gas within the equipment which is incommunication with the outlet structure 19 is partially or completelyexited to the surrounding. Under this circumstance, the pressure of theequipment is reduced.

FIGS. 7A to 7E schematically illustrate the gas-collecting actions ofthe miniature pneumatic device of FIG. 2A. Please refer to FIGS. 1A, 2Aand 7A to 7E. As shown in FIG. 7A, the miniature pneumatic device 1comprises the miniature fluid control device 1A and the miniature valvedevice 1B. As mentioned above, the gas inlet plate 11, the resonanceplate 12, the piezoelectric actuator 13, the first insulation plate 141,the conducting plate 15, the second insulation plate 142 and the gascollecting plate 16 of the miniature fluid control device 1A are stackedon each other sequentially. There is a gap g0 between the resonanceplate 12 and the piezoelectric actuator 13. Moreover, the first chamber121 is formed between the resonance plate 12 and the piezoelectricactuator 13. The valve plate 17 and the gas outlet plate 18 of theminiature valve device 1B are stacked on each other and disposed underthe gas collecting plate 16 of the miniature fluid control device 1A.The gas-collecting chamber 162 is arranged between the gas collectingplate 16 and the piezoelectric actuator 13. The first pressure-releasingchamber 165 and the first outlet chamber 166 are formed in the secondsurface 161 of the gas collecting plate 16. The secondpressure-releasing chamber 183 and the second outlet chamber 184 areformed in the first surface 180 of the gas outlet plate 18. In anembodiment, the operating frequency of the miniature pneumatic device 1is in the range between 27 kHz and 29.5 kHz, and the operating voltageof the miniature pneumatic device 1 is in the range between ±10V and±16V. Moreover, due to the arrangements of the plural pressure chambers,the actuation of the piezoelectric actuator 13 and the vibration of theplate 12 and the valve plate 17, the gas can be transferred downwardly.

As shown in FIG. 7B, the piezoelectric actuator 13 of the miniaturefluid control device 1A is vibrated downwardly in response to theapplied voltage. Consequently, the gas is fed into the miniature fluidcontrol device 1A through the at least one inlet 110 of the gas inletplate 11. The gas is sequentially converged to the central cavity 111through the at least one convergence channel 112 of the gas inlet plate11, transferred through the central aperture 120 of the resonance plate12, and introduced downwardly into the first chamber 121.

As the piezoelectric actuator 13 is actuated, the resonance of theresonance plate 12 occurs. Consequently, the resonance plate 12 is alsovibrated along the vertical direction in the reciprocating manner. Asshown in FIG. 7C, the resonance plate 12 is vibrated downwardly andcontacted with the bulge 130 c of the suspension plate 130 of thepiezoelectric actuator 13. Due to the deformation of the resonance plate12, the volume of the chamber corresponding to the central cavity 111 ofthe gas inlet plate 11 is expanded but the volume of the first chamber121 is shrunken. Under this circumstance, the gas is pushed towardperipheral regions of the first chamber 121. Consequently, the gas istransferred downwardly through the vacant space 135 of the piezoelectricactuator 13. Then, the gas is transferred to the gas-collecting chamber162 between the miniature fluid control device 1A and the miniaturevalve device 1B. Then, the gas is transferred downwardly to the firstpressure-releasing chamber 165 and the first outlet chamber 166 throughthe first perforation 163 and the second perforation 164, which are incommunication with the gas-collecting chamber 162. Consequently, whenthe resonance plate 12 is vibrated along the vertical direction in thereciprocating manner, the gap g0 between the resonance plate 12 and thepiezoelectric actuator 13 is helpful to increase the amplitude of theresonance plate 12. That is, due to the gap g0 between the resonanceplate 12 and the piezoelectric actuator 13, the amplitude of theresonance plate 12 is increased when the resonance occurs.

As shown in FIG. 7D, the resonance plate 12 of the miniature fluidcontrol device 1A is returned to its original position, and thepiezoelectric actuator 13 is vibrated upwardly in response to theapplied voltage. The difference x between the gap g0 and the vibrationdisplacement d of the piezoelectric actuator 13 is given by a formula:x=g0−d. A series of tests about the maximum output pressure of theminiature pneumatic device 1 corresponding to different values of x areperformed. The operating frequency of the miniature pneumatic device 1is in the range between 27 kHz and 29.5 kHz, and the operating voltageof the miniature pneumatic device 1 is in the range between ±10V and±16V. In case that x=1˜5 μm, the maximum output pressure of theminiature pneumatic device 1 is at least 300 mmHg. Consequently, thevolume of the first chamber 121 is also shrunken, and the gas iscontinuously pushed toward peripheral regions of the first chamber 121.Moreover, the gas is continuously transferred to the gas-collectingchamber 162, the first pressure-releasing chamber 165 and the firstoutlet chamber 166 through the vacant space 135 of the piezoelectricactuator 13. Consequently, the pressure in the first pressure-releasingchamber 165 and the first outlet chamber 166 will be graduallyincreased. In response to the increased gas pressure, the flexible valveplate 17 is subjected to the downward curvy deformation. Consequently,the valve plate 17 corresponding to the second pressure-releasingchamber 183 is moved downwardly and contacted with the convex structure181 a corresponding to the first end of the pressure-releasingperforation 181. Under this circumstance, the pressure-releasingperforation 181 of the gas outlet plate 18 is closed. In the secondoutlet chamber 184, the valve opening 170 of the valve plate 17corresponding to the outlet perforation 182 is opened downwardly. Then,the gas within the second outlet chamber 184 is transferred downwardlyto the outlet structure 19 through the outlet perforation 182 and thentransferred to the equipment which is in communication with the outletstructure 19. Consequently, the purpose of collecting the gas pressureis achieved.

Then, as shown in FIG. 7E, the resonance plate 12 of the miniature fluidcontrol device 1A is vibrated upwardly. Under this circumstance, the gasin the central cavity 111 of the gas inlet plate 11 is transferred tothe first chamber 121 through the central aperture 120 of the resonanceplate 12, and then the gas is transferred downwardly to the gascollecting plate 16 through the vacant space 135 of the piezoelectricactuator 13. As the gas pressure is continuously increased along thedownward direction, the gas is continuously transferred to thegas-collecting chamber 162, the second perforation 164, the first outletchamber 166, the second outlet chamber 184 and the outlet perforation182 and then transferred to the equipment which is in communication withthe outlet structure 19. In other words, the pressure-collectingoperation is triggered by the pressure difference between the ambientpressure and the inner pressure of the equipment.

FIG. 8 schematically illustrate the gas-releasing actions or thepressure-reducing actions of the miniature pneumatic device of FIG. 1A.In case that the inner pressure of the equipment which is incommunication with the outlet structure 19 is higher than the ambientair pressure, the gas-releasing operation (or a pressure-reducingoperation) may be performed. As mentioned above, the user may adjust theamount of the gas to be fed into the miniature fluid control device 1A,so that the gas is no longer transferred to the gas-collecting chamber162. Under this circumstance, the gas is transferred from the outletstructure 19 to the second outlet chamber 184 through the outletperforation 182. Consequently, the volume of the second outlet chamber184 is expanded, and the flexible valve plate 17 corresponding to thesecond outlet chamber 184 is bent upwardly. In addition, the valve plate17 is in close contact with the raised structure 167 corresponding tothe first outlet chamber 166. Since the valve opening 170 of the valveplate 17 is closed by the raised structure 167, the gas in the secondoutlet chamber 184 will not be reversely returned to the first outletchamber 166. Moreover, the gas in the second outlet chamber 184 istransferred to the second pressure-releasing chamber 183 through thecommunication channel 185, and then the gas in the secondpressure-releasing chamber 183 is transferred to the pressure-releasingperforation 181. Under this circumstance, the gas-releasing operation isperformed. After the gas-releasing operation of the miniature valvedevice 1B in one direction is performed, the gas within the equipmentwhich is in communication with the outlet structure 19 is partially orcompletely exited to the surrounding. Under this circumstance, the innerpressure of the equipment is reduced.

In the embodiment, the suspension plate 130 is a square suspensionplate. As the side length of the square suspension plate 130 isdecreased, the area of the suspension plate 130 is reduced.Consequently, the rigidity of the suspension plate 130 is enhanced. Inaddition, the efficacy of pushing or compressing the gas is increaseddue to that the volume of the gas channel is reduced. Consequently, theoutput pressure is increased. Furthermore, the deformation amount of thesuspension plate in the horizontal direction is reduced in response tothe vertical vibration of the suspension plate, so that the vibration ofthe suspension plate is maintained in the vertical direction and thepiezoelectric actuator is not readily inclined during vibration.Consequently, the collision interference between the piezoelectricactuator and the resonance plate or other component can be reduced.Under this circumstance, the noise is reduced, and the defect rate isreduced. To sum up, as the size of the suspension plate is reduced, thesize of the piezoelectric actuator can be correspondingly reduced.Consequently, the performance and maximum output pressure of theminiature pneumatic device are increased, the noise is reduced, and thedefect rate is reduced. On the contrary, as the size of the suspensionplate is increased, the defect rate of the miniature pneumatic device isincreased and the output pressure is reduced.

The suspension plate and the piezoelectric ceramic plate are coreelements of the miniature pneumatic device. By reducing the size of thesuspension plate and the size of the piezoelectric ceramic plate, thesize and weight of the miniature pneumatic device are reducedcorrespondingly. Consequently, the miniature pneumatic device can beinstalled in a portable device easily and the applicability of theminiature pneumatic device is not limited.

After the miniature fluid control device 1A and the miniature valvedevice 1B are combined together, the total thickness of the miniaturepneumatic device 1 is in the range between 2 mm and 6 mm. Since theminiature pneumatic device is slim and portable, the miniature pneumaticdevice is suitably applied to medical equipment or any other appropriateequipment.

From the above descriptions, the present invention provides apiezoelectric actuator for a miniature fluid control device. Theminiature fluid control device and the miniature valve device areemployed in the miniature pneumatic device. After the gas is fed intothe miniature fluid control device through the inlet, the piezoelectricactuator is actuated. Consequently, a pressure gradient is generated inthe fluid channels of the miniature fluid control device and thegas-collecting chamber to facilitate the gas to flow to the miniaturevalve device at a high speed. Moreover, due to the one-way valve plateof the miniature valve device, the gas is transferred in one direction.Consequently, the pressure of the gas is accumulated to any equipmentthat is connected with the outlet structure. For performing agas-releasing operation (or a pressure-reducing operation), the user mayadjust the amount of the gas to be fed into the miniature fluid controldevice, so that the gas is no longer transferred to the gas-collectingchamber. Under this circumstance, the gas is transferred from the outletstructure to the second outlet chamber of the miniature valve device,then transferred to the second pressure-releasing chamber through thecommunication channel, and finally exited from the pressure-releasingperforation. By the miniature pneumatic device of the present invention,the gas can be quickly transferred while achieving silent efficacy.Moreover, due to the special configurations, the miniature pneumaticdevice of the present invention has small volume and small thickness.Consequently, the miniature pneumatic device is portable and applied tomedical equipment or any other appropriate equipment. In other words,the miniature pneumatic device of the present invention has industrialvalues.

While the invention has been described in terms of what is presentlyconsidered to be the most practical and preferred embodiments, it is tobe understood that the invention needs not be limited to the disclosedembodiment. On the contrary, it is intended to cover variousmodifications and similar arrangements included within the spirit andscope of the appended claims which are to be accorded with the broadestinterpretation so as to encompass all such modifications and similarstructures.

What is claimed is:
 1. A piezoelectric actuator, comprising: a suspension plate, wherein the suspension plate is a square structure, a length of the suspension plate is in a range between 4 mm and 8 mm, and the suspension plate is permitted to undergo a curvy vibration from a middle portion to a periphery portion; a piezoelectric ceramic plate, wherein the piezoelectric ceramic plate is a square structure, a length of the piezoelectric ceramic plate is not larger than a length of the suspension plate, and the piezoelectric ceramic plate is attached on a first surface of the suspension plate, wherein when a voltage is applied to the piezoelectric ceramic plate, the suspension plate is driven to undergo the curvy vibration; an outer frame arranged around the suspension plate; and at least one bracket connected between the suspension plate and the outer frame for elastically supporting the suspension plate, wherein the bracket comprises: an intermediate part formed in a vacant space between the suspension plate and the outer frame and in parallel with the outer frame and the suspension plate; a first connecting part arranged between the intermediate part and the suspension plate; and a second connecting part arranged between the intermediate part and the outer frame, wherein the first connecting part and the second connecting part are opposed to each other and arranged along the same horizontal line.
 2. The piezoelectric actuator according to claim 1, wherein the at least one bracket is a connecting part connected between the suspension plate and the outer frame.
 3. The piezoelectric actuator according to claim 2, wherein the connecting part has two ends, and the two ends are opposed to each other and arranged along the same horizontal line.
 4. The piezoelectric actuator according to claim 2, wherein the connecting part is connected with the outer frame and the suspension plate at an inclined angle between 0 to 45 degrees.
 5. The piezoelectric actuator according to claim 1, wherein the length of the suspension plate is in a range between 4 mm and 6 mm.
 6. The piezoelectric actuator according to claim 1, wherein the length of the suspension plate is in a range between 6 mm and 7.5 mm.
 7. The piezoelectric actuator according to claim 1, wherein the length of the suspension plate is in a range between 7.5 mm and 8 mm.
 8. The piezoelectric actuator according to claim 1, wherein the suspension plate further comprises a bulge, and the bulge is formed on a second surface of the suspension plate.
 9. The piezoelectric actuator according to claim 8, wherein, wherein a thickness of the bulge is in a range between 0.02 mm and 0.08 mm.
 10. The piezoelectric actuator according to claim 8, wherein the bulge is a circular convex structure, and a diameter of the bulge is 0.55 times as large as a short side length of the suspension plate.
 11. The piezoelectric actuator according to claim 1, wherein a thickness of the suspension plate is in a range between 0.1 mm and 0.4 mm.
 12. The piezoelectric actuator according to claim 1, wherein a thickness of the piezoelectric ceramic plate is in a range between 0.05 mm and 0.3 mm. 